Conventional ventilated seats include a seat trim cover made of fabric or leather on which a seat occupant's body contacts, and an air permeable layer located under the seat cover. The air permeable layer rests on a cushioning element, for example a bun of polyurethane foam, coconut fiber, cotton mat, etc. An air manifold conducts air flow into or out of the air permeable layer or the whole cushioning element. In such seats, the source of the air pressure or partial vacuum (fan, blower, seat air conditioning unit or a ducting from a vehicular air conditioning unit) is connected to the seat internal manifold.
The cushioning element of the seat is typically supported by a seat structure including a frame that may be stationary or flexing. Examples of the supporting structure include steel springs, plywood sheeting, a “seat pan” (in automotive seats), and other structural materials.
One technical difficulty in the field of ventilated seats is the structure and arrangement of the manifold for delivery and/or exhaust of air to and from the air permeable elements of the seat.
Conventional air manifolds may be one of two major types. The first type of manifold is a ribbon-shape extension of the air permeable layer that is wrapped with air-tight material and routed inside the seat to the air mover or external ducting port. This “porous” manifold exhibits significant hydraulic resistance, limiting the airflow and thus the ventilation efficiency.
The second type of manifold is an arrangement of ducts inside the cushioning element. This type of manifold includes ducts disposed in a direction parallel to the sitting surface. This manifold does not limit the air flow in an unoccupied seat. However, the lateral duct partitions of this type of manifold are prone to collapsing when the weight of a seat occupant applies excessive force against the seat or when the cushioning element becomes softer with age, thereby reducing the performance of the manifold.